ACS Earth and Space Chemistry最新文献

{"title":"Fe/Mg-Silicate Chemical Gardens as Analogs to Silicate-Rich Hydrothermal Chimneys on Early Earth and Mars","authors":"Nancy A. Carman*,&nbsp;Elisabeth M. Hausrath,&nbsp;Aaron Celestian,&nbsp;Julia Chavez,&nbsp;Ninos Hermis,&nbsp;Douglas E. LaRowe,&nbsp;Abigail A. Fraeman,&nbsp;Rachel Y. Sheppard,&nbsp;Christopher T. Adcock,&nbsp;Oliver Tschauner,&nbsp;Elizabeth B. Rampe,&nbsp;Roy Price and Laura M. Barge*,&nbsp;","doi":"10.1021/acsearthspacechem.4c0010910.1021/acsearthspacechem.4c00109","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.4c00109https://doi.org/10.1021/acsearthspacechem.4c00109","url":null,"abstract":"<p >Hydrothermal systems have been proposed as environments for prebiotic chemistry on early Earth. Ancient Mars had surface water and could also have had hydrothermal vents supporting biological or prebiotic processes. The Strýtan hydrothermal field (SHF) in Iceland is a basalt-hosted alkaline vent that forms massive hydrothermal Mg-saponite chimneys and is a potential analog to basalt-hosted alkaline vents that may have existed at the Eridania basin on Mars, where Fe/Mg-phyllosilicate deposits (e.g., saponite, talc, sepiolite, and serpentine) are thought to have formed from ancient hydrothermal activity. Chemical garden experiments have previously been used to simulate aspects of hydrothermal chimney growth for other types of vent systems; however, they have not been much used in this context of a silica-rich hydrothermal system. Here, we studied the formation of Fe/Mg-silicate injection chemical gardens simulating hydrothermal chimneys that represent analogs of precipitates that could have formed in SHF-like hydrothermal vents on early Earth and/or early Mars. We found that the Fe/Mg ratio of the exterior (ocean simulant) solutions influenced the simulated chimney chemistry under anoxic conditions and that the precipitates were enriched with Fe compared to the surrounding solution. Simulated chimney compositions as analyzed by Raman spectroscopy, scanning electron microscope-energy dispersive X-ray spectroscopy, X-ray diffraction, and visible–near-infrared reflectance spectroscopy were also affected by whether the chimneys were dried and/or heated post formation. Our data were suggestive of the presence of poorly ordered Mg-clay-like phases (e.g., sepiolite) in the simulated chimneys, along with amorphous/nanocrystalline Fe phases and Fe oxides/hydroxides, hydrated silica, hematite, halite, and gypsum. Saponite was not produced in our experiments because of an absence of Al in solution. Though we observed evidence for Mg-silicate and clay-like minerals in the chemical gardens, we only observed weak 12.5 Å peaks for Fe-silicate or Fe-containing clay-like minerals; however, amorphous silica and Fe oxides/hydroxides were confirmed, similar to what has been observed in previous chemical garden studies. This suggests that in SHF-like chimneys on early Earth and/or Mars, Mg would have been present as Mg-hydroxides and Mg-silicates (and, in the presence of additional geological components such as Al, likely saponite or other aluminous clay minerals), whereas Fe would be present as Fe or Fe:Mg-hydroxides. Such chimneys, containing both reactive Fe hydroxides as well as Mg-clay-like phases, would have increased potential for mineral-driven prebiotic chemical reactions.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142450817","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of Biochar on the Fe(II)aq-Catalyzed Transformation of Ferrihydrite","authors":"Ning Liu, Yongdong Zhang, Manjia Chen, Qinkai Lei, Leheng Dong, Hui Tong, Chengshuai Liu, Huanyun Yu","doi":"10.1021/acsearthspacechem.4c00133","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.4c00133","url":null,"abstract":"The abiotic transformation of an amorphous iron (Fe) hydroxide hydrate to more crystalline Fe(III) minerals by Fe(II) plays an essential role in global Fe cycling. In natural environments, Fe(III) minerals generally coexist with organic matter, which modulates their mineralization pathways and byproducts. Nevertheless, the effect of exogenous organic matter, such as biochar, on the transformation of Fe(III) minerals remains unclear. In this study, a series of ferrihydrite-biochar complexes (Fh-BCs) with various C/Fe molar ratios were synthesized to evaluate the abiotic Fe(II)-catalyzed mineralogical transformation of Fh-BCs under neutral anaerobic conditions. During the synthesis of Fh-BC, biochar formed a complex with Fh through adsorption onto Fh at a C/Fe ratio of 0.3, whereas Fh loaded onto biochar with a C/Fe ratio of 1.2 generated the Fh-BC-1.2 complex. Compared to pure Fh, the specific surface area and total pore volume decreased in all of the Fh-BCs. The secondary mineral formation during Fh transformation depended on the C/Fe ratios. Biochar inhibited the formation of magnetite (Mgt) but not lepidocrocite (Lep) in the treatments of Fh-BC + Fe(II). However, the inhibition level of Mgt formation was negatively correlated with the C/Fe ratio. Experiments analyzing the time-dependent concentrations of Fe(II) and labile Fe(III) (Fe(III)_labile) against the kinetics of phase transformation showed that the occupation of adsorption sites on the surface of Fh by biochar inhibited electron exchange between Fh and Fe(II), thereby preventing the hydrolysis–reprecipitation of Fh into the more stable mineral phase. High C/Fe ratios modestly enhanced the transformation of Fh, which was attributed to the Fh-loaded structure that facilitated Fe(II) sorption and promoted efficient electron transfer between Fe(II) and Fh. These results indicate that biochar-modified Fh is favorable to the phase transformation of stable crystalline Fe(III) minerals, possibly providing new insight into the geochemical behavior of Fe/C cycling in carbon-rich soil environments.","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142257862","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of Biochar on the Fe(II)aq-Catalyzed Transformation of Ferrihydrite","authors":"Ning Liu,&nbsp;Yongdong Zhang,&nbsp;Manjia Chen*,&nbsp;Qinkai Lei,&nbsp;Leheng Dong,&nbsp;Hui Tong*,&nbsp;Chengshuai Liu and Huanyun Yu,&nbsp;","doi":"10.1021/acsearthspacechem.4c0013310.1021/acsearthspacechem.4c00133","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.4c00133https://doi.org/10.1021/acsearthspacechem.4c00133","url":null,"abstract":"<p >The abiotic transformation of an amorphous iron (Fe) hydroxide hydrate to more crystalline Fe(III) minerals by Fe(II) plays an essential role in global Fe cycling. In natural environments, Fe(III) minerals generally coexist with organic matter, which modulates their mineralization pathways and byproducts. Nevertheless, the effect of exogenous organic matter, such as biochar, on the transformation of Fe(III) minerals remains unclear. In this study, a series of ferrihydrite-biochar complexes (Fh-BCs) with various C/Fe molar ratios were synthesized to evaluate the abiotic Fe(II)-catalyzed mineralogical transformation of Fh-BCs under neutral anaerobic conditions. During the synthesis of Fh-BC, biochar formed a complex with Fh through adsorption onto Fh at a C/Fe ratio of 0.3, whereas Fh loaded onto biochar with a C/Fe ratio of 1.2 generated the Fh-BC-1.2 complex. Compared to pure Fh, the specific surface area and total pore volume decreased in all of the Fh-BCs. The secondary mineral formation during Fh transformation depended on the C/Fe ratios. Biochar inhibited the formation of magnetite (Mgt) but not lepidocrocite (Lep) in the treatments of Fh-BC + Fe(II). However, the inhibition level of Mgt formation was negatively correlated with the C/Fe ratio. Experiments analyzing the time-dependent concentrations of Fe(II) and labile Fe(III) (Fe(III)_labile) against the kinetics of phase transformation showed that the occupation of adsorption sites on the surface of Fh by biochar inhibited electron exchange between Fh and Fe(II), thereby preventing the hydrolysis–reprecipitation of Fh into the more stable mineral phase. High C/Fe ratios modestly enhanced the transformation of Fh, which was attributed to the Fh-loaded structure that facilitated Fe(II) sorption and promoted efficient electron transfer between Fe(II) and Fh. These results indicate that biochar-modified Fh is favorable to the phase transformation of stable crystalline Fe(III) minerals, possibly providing new insight into the geochemical behavior of Fe/C cycling in carbon-rich soil environments.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142450756","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental Gas-Phase Removal of OH Radicals in the Presence of NH2C(O)H over the 11.7–353 K Range: Implications in the Chemistry of the Interstellar Medium and the Earth’s Atmosphere","authors":"Daniel González, Sara Espinosa, María Antiñolo, Marcelino Agúndez, José Cernicharo, Sydney Willis, Robin T. Garrod, Elena Jiménez","doi":"10.1021/acsearthspacechem.4c00082","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.4c00082","url":null,"abstract":"Formamide (NH₂C(O)H) has been observed both in the interstellar medium (ISM), being identified as a potential precursor of prebiotic molecules in space, and in the Earth’s atmosphere. In these environments where temperature is very distinct, hydroxyl (OH) radicals may play an important role in the degradation of NH₂C(O)H. Thus, in this work, we report for the first time the experimental study of the temperature dependence of the gas-phase removal of OH in the presence of NH₂C(O)H over the 11.7–353 K range. In the lowest temperature range (11.7–177.5 K), of interest for the ISM chemistry, the kinetic study was performed using a pulsed CRESU (French acronym for Reaction Kinetics in a Uniform Supersonic Flow) apparatus, while a thermostatized slow-flow reactor was employed in the kinetic study of the OH + NH₂C(O)H reaction over the 273–353 K range, of interest in the Earth’s troposphere below room temperature. The pulsed laser photolysis at 248 nm of a suitable OH-precursor (hydrogen peroxide, <i>tert</i>-butyl hydroperoxide, or acetylacetone) was used to generate OH radicals in the reactor. The temporal evolution of OH was monitored by laser-induced fluorescence at 310 nm. An almost independent <i>k</i>(<i>T</i>) between 273 and 353 K (temperatures of the Earth’s troposphere extended to <i>T</i> &gt; 298 K) is reported, being the OH + NH₂C(O)H reaction the major degradation route with an atmospheric lifetime of around 1 day. At lower temperatures of interest in the ISM (11.7–177.5 K), the potential formation of NH₂C(O)H dimers was evaluated. Thermodynamically, under equilibrium conditions, formamide would be fully converted into the dimer in that <i>T</i> range. However, the qualitative agreement of the observed increase of <i>k</i>(<i>T</i>) with computational studies on the OH + NH₂C(O)H reaction down to 200 K let us to report, between 177.5 and 106.0 K, the following parameters commonly used in astrochemical modeling: α = (3.76 ± 0.62) × 10^–12 cm³ s^–1, β = (3.07 ± 0.11), and γ = 0. At 11.7 K, a kinetic model reproducing the experimental data indicates that formamide dimerization could be important, but the OH-reaction with the monomer would be fast, 4 × 10^–10 cm³ s^–1, and the OH-reaction with the dimer, relatively slow [(0.1–1.0) × 10^–11 cm³ s^–1]. Despite that, the impact of the gas-phase OH + NH₂C(O)H in the relative abundances of NH₂C(O)H in a dense molecular cloud (<i>T</i> ∼ 10 K) and after the warm-up phase in the surroundings of hot cores/corinos (here, 10–400 K) appears to be negligible.","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142257861","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental Gas-Phase Removal of OH Radicals in the Presence of NH2C(O)H over the 11.7–353 K Range: Implications in the Chemistry of the Interstellar Medium and the Earth’s Atmosphere","authors":"Daniel González,&nbsp;Sara Espinosa,&nbsp;María Antiñolo,&nbsp;Marcelino Agúndez,&nbsp;José Cernicharo,&nbsp;Sydney Willis,&nbsp;Robin T. Garrod and Elena Jiménez*,&nbsp;","doi":"10.1021/acsearthspacechem.4c0008210.1021/acsearthspacechem.4c00082","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.4c00082https://doi.org/10.1021/acsearthspacechem.4c00082","url":null,"abstract":"<p >Formamide (NH₂C(O)H) has been observed both in the interstellar medium (ISM), being identified as a potential precursor of prebiotic molecules in space, and in the Earth’s atmosphere. In these environments where temperature is very distinct, hydroxyl (OH) radicals may play an important role in the degradation of NH₂C(O)H. Thus, in this work, we report for the first time the experimental study of the temperature dependence of the gas-phase removal of OH in the presence of NH₂C(O)H over the 11.7–353 K range. In the lowest temperature range (11.7–177.5 K), of interest for the ISM chemistry, the kinetic study was performed using a pulsed CRESU (French acronym for Reaction Kinetics in a Uniform Supersonic Flow) apparatus, while a thermostatized slow-flow reactor was employed in the kinetic study of the OH + NH₂C(O)H reaction over the 273–353 K range, of interest in the Earth’s troposphere below room temperature. The pulsed laser photolysis at 248 nm of a suitable OH-precursor (hydrogen peroxide, <i>tert</i>-butyl hydroperoxide, or acetylacetone) was used to generate OH radicals in the reactor. The temporal evolution of OH was monitored by laser-induced fluorescence at 310 nm. An almost independent <i>k</i>(<i>T</i>) between 273 and 353 K (temperatures of the Earth’s troposphere extended to <i>T</i> &gt; 298 K) is reported, being the OH + NH₂C(O)H reaction the major degradation route with an atmospheric lifetime of around 1 day. At lower temperatures of interest in the ISM (11.7–177.5 K), the potential formation of NH₂C(O)H dimers was evaluated. Thermodynamically, under equilibrium conditions, formamide would be fully converted into the dimer in that <i>T</i> range. However, the qualitative agreement of the observed increase of <i>k</i>(<i>T</i>) with computational studies on the OH + NH₂C(O)H reaction down to 200 K let us to report, between 177.5 and 106.0 K, the following parameters commonly used in astrochemical modeling: α = (3.76 ± 0.62) × 10^–12 cm³ s^–1, β = (3.07 ± 0.11), and γ = 0. At 11.7 K, a kinetic model reproducing the experimental data indicates that formamide dimerization could be important, but the OH-reaction with the monomer would be fast, 4 × 10^–10 cm³ s^–1, and the OH-reaction with the dimer, relatively slow [(0.1–1.0) × 10^–11 cm³ s^–1]. Despite that, the impact of the gas-phase OH + NH₂C(O)H in the relative abundances of NH₂C(O)H in a dense molecular cloud (<i>T</i> ∼ 10 K) and after the warm-up phase in the surroundings of hot cores/corinos (here, 10–400 K) appears to be negligible.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/epdf/10.1021/acsearthspacechem.4c00082","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142450814","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High-Resolution UV Absorption Cross-Section Measurements of 32S, 33S, 34S, and 36S Sulfur Dioxide for the B~1B1−X~1A1 Absorption Band","authors":"Yuanzhe Li, Sebastian O. Danielache, Yoshiaki Endo, Shinkoh Nanbu, Yuichiro Ueno","doi":"10.1021/acsearthspacechem.4c00147","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.4c00147","url":null,"abstract":"We report newly measured high-resolution and high-precision ultraviolet absorption cross-sections of ³²SO₂, ³³SO₂, ³⁴SO₂, and ³⁶SO₂ for the <i></i><math display=\"inline\" overflow=\"scroll\"><msup><mover><mi>B</mi><mo accent=\"true\" stretchy=\"false\">~</mo></mover><mn>1</mn></msup><msub><mi>B</mi><mn>1</mn></msub><mo>−</mo><msup><mover><mi>X</mi><mo accent=\"true\" stretchy=\"false\">~</mo></mover><mn>1</mn></msup><msub><mi>A</mi><mn>1</mn></msub></math> band over the wavelength range of 240 to 320 nm at a resolution of 0.4 cm^–1. The resolution was improved 20 times compared to that in a previous study. A least absolute deviation linear regression method was applied to calculate cross-sections and derived spectral errors from a set of measurements recorded at a wide range of pressures to ensure the optimal signal-to-noise ratio at all wavelengths. Based on this analysis, error bars on the measured cross-sections ranged between 3 and 10%. The overall features of measured cross-sections, such as peak positions of the isotopologues, are consistent with previous studies. We provide improved spectral data for studying sulfur mass-independent fraction (S-MIF) signatures during SO₂ photoexcitation. Our spectral measurements predict that SO₂ photoexcitation produces S-MIF enrichment factors ³³<i>E</i> = – 0.9 ± 0.2‰ and ³⁶<i>E</i> = – 3.8 ± 0.4‰ (where ³³<i>E</i> and ³⁶<i>E</i> are 1000 × [ln(³³<i>J</i>/³²<i>J</i>) – 0.515 ln(³⁴<i>J</i>/³²<i>J</i>)] ‰ and 1000 × [ln(³⁶<i>J</i>/³²<i>J</i>) – 1.90 ln(³⁴<i>J</i>/³²<i>J</i>] ‰, and ^3<i>x</i><i>J</i> is the ^3<i>x</i>SO₂ photoexcitation rate constant). Based on this new result, we found that calculated SO₂ photoexcitation isotope effects are smaller than previously thought and generally do not match photoexcitation experimental observations supporting the hypothesis of an intersystem crossing origin of MIF on those experiments.","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142257860","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High-Resolution UV Absorption Cross-Section Measurements of 32S, 33S, 34S, and 36S Sulfur Dioxide for the B~1B1−X~1A1 Absorption Band","authors":"Yuanzhe Li*,&nbsp;Sebastian O. Danielache*,&nbsp;Yoshiaki Endo,&nbsp;Shinkoh Nanbu and Yuichiro Ueno,&nbsp;","doi":"10.1021/acsearthspacechem.4c0014710.1021/acsearthspacechem.4c00147","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.4c00147https://doi.org/10.1021/acsearthspacechem.4c00147","url":null,"abstract":"<p >We report newly measured high-resolution and high-precision ultraviolet absorption cross-sections of ³²SO₂, ³³SO₂, ³⁴SO₂, and ³⁶SO₂ for the <i></i><math><msup><mover><mi>B</mi><mo>~</mo></mover><mn>1</mn></msup><msub><mi>B</mi><mn>1</mn></msub><mo>−</mo><msup><mover><mi>X</mi><mo>~</mo></mover><mn>1</mn></msup><msub><mi>A</mi><mn>1</mn></msub></math> band over the wavelength range of 240 to 320 nm at a resolution of 0.4 cm^–1. The resolution was improved 20 times compared to that in a previous study. A least absolute deviation linear regression method was applied to calculate cross-sections and derived spectral errors from a set of measurements recorded at a wide range of pressures to ensure the optimal signal-to-noise ratio at all wavelengths. Based on this analysis, error bars on the measured cross-sections ranged between 3 and 10%. The overall features of measured cross-sections, such as peak positions of the isotopologues, are consistent with previous studies. We provide improved spectral data for studying sulfur mass-independent fraction (S-MIF) signatures during SO₂ photoexcitation. Our spectral measurements predict that SO₂ photoexcitation produces S-MIF enrichment factors ³³<i>E</i> = – 0.9 ± 0.2‰ and ³⁶<i>E</i> = – 3.8 ± 0.4‰ (where ³³<i>E</i> and ³⁶<i>E</i> are 1000 × [ln(³³<i>J</i>/³²<i>J</i>) – 0.515 ln(³⁴<i>J</i>/³²<i>J</i>)] ‰ and 1000 × [ln(³⁶<i>J</i>/³²<i>J</i>) – 1.90 ln(³⁴<i>J</i>/³²<i>J</i>] ‰, and ^3<i>x</i><i>J</i> is the ^3<i>x</i>SO₂ photoexcitation rate constant). Based on this new result, we found that calculated SO₂ photoexcitation isotope effects are smaller than previously thought and generally do not match photoexcitation experimental observations supporting the hypothesis of an intersystem crossing origin of MIF on those experiments.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/epdf/10.1021/acsearthspacechem.4c00147","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142450646","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Metal Monoxide Abundances as a Function of the C/O Ratio","authors":"Gerard Meijer, Gert von Helden","doi":"10.1021/acsearthspacechem.4c00175","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.4c00175","url":null,"abstract":"The diatomic metal monoxides whose optical spectra define the classification of stars on the asymptotic giant branch (AGB), that is, TiO, YO, ZrO, and LaO, have the unusual property that their ionization energy is below their dissociation limit. The cations of these metal monoxides can be efficiently produced via the associative ionization of their constituent ground state atoms and are long-lived. We present a simple model that can explain the observed relative abundance of these metal oxides as a function of the C/O ratio.","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142179685","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Metal Monoxide Abundances as a Function of the C/O Ratio","authors":"Gerard Meijer*,&nbsp; and ,&nbsp;Gert von Helden,&nbsp;","doi":"10.1021/acsearthspacechem.4c0017510.1021/acsearthspacechem.4c00175","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.4c00175https://doi.org/10.1021/acsearthspacechem.4c00175","url":null,"abstract":"<p >The diatomic metal monoxides whose optical spectra define the classification of stars on the asymptotic giant branch (AGB), that is, TiO, YO, ZrO, and LaO, have the unusual property that their ionization energy is below their dissociation limit. The cations of these metal monoxides can be efficiently produced via the associative ionization of their constituent ground state atoms and are long-lived. We present a simple model that can explain the observed relative abundance of these metal oxides as a function of the C/O ratio.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/epdf/10.1021/acsearthspacechem.4c00175","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142273776","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Harvest Initiated Volatile Organic Compound Emissions from In-Field Tall Wheatgrass","authors":"Gregory W. Vandergrift, Sheryl L. Bell, Shannon E. Schrader, Sonja M. Jensen, Jon H. Wahl, Jerry D. Tagestad, Swarup China, Kirsten S. Hofmockel","doi":"10.1021/acsearthspacechem.4c00046","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.4c00046","url":null,"abstract":"While crop and grassland usage continues to increase, the full diversity of plant-specific volatile organic compounds (VOCs) emitted from these ecosystems, including their implications for atmospheric chemistry and carbon cycling, remains poorly understood. It is particularly important to investigate VOCs in the context of potential biofuels: aside from the implications of large-scale land use, harvest may shift both the flux and speciation of emitted VOCs. To this point, we evaluate the diversity of VOCs emitted both pre and postharvest from “Alkar” tall wheatgrass (<i>Thinopyrum ponticum</i>), a candidate biofuel that exhibits greater tolerance to frost and saline land compared to other grass varieties. Mature plants grown under field conditions (<i>n</i> = 6) were sampled for VOCs both pre- and postharvest (October 2022). Via hierarchical clustering of emitted VOCs from each plant, we observe distinct “volatilomes” (diversity of VOCs) specific to the pre- and postharvest conditions despite plant-to-plant variability. In total, 50 VOCs were found to be unique to the postharvest tall wheatgrass volatilome, and these unique VOCs constituted a significant portion (26%) of total postharvest signal. While green leaf volatiles (GLVs) dominate the speciation of postharvest emissions (e.g., 54% of unique postharvest VOC signal was due to 1-penten-3-ol), we demonstrate novel postharvest VOCs from tall wheatgrass that are under characterized in the context of carbon cycling and atmospheric chemistry (e.g., 3-octanone). Continuing evaluations will quantitatively investigate tall wheatgrass VOC fluxes, better informing the feasibility and environmental impact of tall wheatgrass as a biofuel.","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142179687","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}